In addition, representatives from the phylum Bacteroidetes encoded endothelin-converting enzyme 1 precursor, which plays a significant role in cardiovascular diseases and Alzheimer’s disease in humans [41], 3-oxo-5-α-steroid 4-dehydrogenase capable of modification of steroid hormones or bile [42], or glutamate decarboxylase catalysing production of γ-aminobutyrate (GABA), a mediator within the enteric nervous system [43]. Here, ECE1 is linked to early-onset autosomal dominant Alzheimer disease.